Welcome! Log In Create A New Profile Recent Messages

Advanced

4x4 systems tests

Posted by jaffar 
November 05, 2014 08:48AM
Interesting stuff - most of the 4WD/AWD systems on the market are busted when oen side of the car has no traction:

[www.youtube.com]

--
A physics truck just turned over outside. There's physics everywhere!
November 05, 2014 09:46AM
Quote
jaffar
Interesting stuff - most of the 4WD/AWD systems on the market are busted when oen side of the car has no traction:

[www.youtube.com]

...unless you can lock the diff? I can't understand what they say, but makes sense to me.

Propper off-road vehicles have a switch to lock the diff and cope with slippery and low traction surfaces, and normal diff for the road.
In normal road conditions, AWD is just extra weight in the car, I believe.
November 06, 2014 01:14PM
I wonder what kind of diffs all those cars had. It looked like they were all open diffs. With a center and rear LSD and open front diff, my 24-year old iX would have passed that test. smiling smiley

__________
Dave
'91 325iX
November 06, 2014 11:08PM
Even the new BMWs won't work like our iXs did. The new cars all have open diffs and open transfer boxes. All traction control is done by braking. Seems that the designers never bothered to check what would happen if two wheels on one side slipped:stickpoke:

Did anyone else notice the X3 or X5 that appeared to be FWD only :laugh:
November 07, 2014 04:26AM
In theory, it can be done by braking, if the ABS/traction control computer knows what the driver wants the car to do.
There is the ABS pipework, sensors and valves in place, is just some more programming.
Most "SUV" and AWD cars today are just glorified FWD designs, with electronic traction control and bigger wheels thrown into it.
Check the Land Rover Evoque, they did a nice job.

I believe the older school LSD are a bit worse for fuel economy.
Is that accurate, or am I wrong?

For those always suspecting electronic stuff and fearing to drive with HAL9000 on board, the old ABS from the benz works fine, the only trouble it had was dirty gunky sensors.
:dance:
November 08, 2014 02:07PM
Quote
Archeo-peteriX
Even the new BMWs won't work like our iXs did. The new cars all have open diffs and open transfer boxes. All traction control is done by braking. Seems that the designers never bothered to check what would happen if two wheels on one side slipped:stickpoke:

Did anyone else notice the X3 or X5 that appeared to be FWD only :laugh:

The first generation X5 had open differentials, but the newer xDrive cars have very complex diffferentials with
computer controlled torque distribution. It is not controlled by braking the wheels.
November 08, 2014 02:54PM
Quote
Ove Kvam
Quote
Archeo-peteriX
Even the new BMWs won't work like our iXs did. The new cars all have open diffs and open transfer boxes. All traction control is done by braking. Seems that the designers never bothered to check what would happen if two wheels on one side slipped:stickpoke:

Did anyone else notice the X3 or X5 that appeared to be FWD only :laugh:

The first generation X5 had open differentials, but the newer xDrive cars have very complex diffferentials with
computer controlled torque distribution. It is not controlled by braking the wheels.

Were any of the cars tested in the video of the xDrive variety?



Edited 1 time(s). Last edit at 11/08/2014 02:55PM by Archeo-peteriX.
November 08, 2014 03:09PM
Quote
Archeo-peteriX
Were any of the cars tested in the video of the xDrive variety?u

I don't know.

The car I currently drive, an F20 1-series 116i, has a wheel brake operated differential brake system when the
stability system is disabled. The differential itself is open. This system works surprisingly well. Compared to a real
differential brake, it allows me to go earlier on the throttle in corners. It does however feel a bit clunky and sluggish
when trying to balance the car sideways.
November 19, 2014 03:17PM
November 19, 2014 08:02PM
That must be the reason I have an F-15 X-5. Has to be something like that anyway.

:burnout:

Bob in Everett
November 20, 2014 05:24AM

Those cars are sold for social "status", not for AWD ability.

hot smiley
November 20, 2014 07:19AM
Quote
Jose Pinto

Those cars are sold for social "status", not for AWD ability.

hot smiley

In Norway, it is a little bit of both. Four wheel drive can be an advantage when driving the family to the
skiing resorts in the winter on snowy roads. There are 2WD versions of some of these SUVs, and they
have the same status since they look similar. They still sell very few of them in Norway, as people prefer
the traction and stability with 4WD.

Personally, I prefer the instability of RWD because it is more fun to drive.
November 20, 2014 08:03AM
Quote
Ove Kvam

In Norway, it is a little bit of both. Four wheel drive can be an advantage when driving the family to the
skiing resorts in the winter on snowy roads. There are 2WD versions of some of these SUVs, and they
have the same status since they look similar. They still sell very few of them in Norway, as people prefer
the traction and stability with 4WD.

Personally, I prefer the instability of RWD because it is more fun to drive.

Those who have a 2WD car are not foolishly relying on some AWD technology that may, or may not be effective when they need it most, and most times they don't know how to use right.

I found many times AWD cars stranded in the mud or snow or whatever, more than 2WD, because they thought the car could deal with it and it couldn't.
November 20, 2014 08:25AM
Quote
Jose Pinto
I found many times AWD cars stranded in the mud or snow or whatever, more than 2WD, because they thought the car could deal with it and it couldn't.

And while AWD cars can often pull 2WD cars back onto the road, a stuck AWD car will usually have to wait hours for some big tractor to come and save it! smiling smiley
November 20, 2014 11:29PM
Sometimes it is because one's spouse wants a new car.
:biggrin:

Bob in Everett
Sorry, only registered users may post in this forum.

Click here to login

Online Users

Guests: 7
Record Number of Users: 3 on September 29, 2015
Record Number of Guests: 109 on June 08, 2017